1. Field of the Invention
This invention relates to data transfer methodologies and, more particularly, to a power state broadcast mechanism.
2. Description of the Related Art
In a typical PC system, particularly in mobile systems, saving power is important. To that end, individual devices within the system usually adjust their power consumption based on the state of system power. If the system has decided to enter a lower power mode, then all devices may also enter a lower power mode.
Most devices that are capable of responding to power state changes dedicate pins to power state signals. In addition, some devices include A/D converters to monitor voltage supplies and determine on their own the power state of the system, e.g., detect that a supply has been shut down and cause the device to enter a low power state.
Dedicating pins to power state signals may be expensive on very small or low-cost parts. The use of A/D converters may involve process changes and considerable chip die area to implement. Direct monitoring of voltages may also require that a device requiring power state control be connected to all voltages, even though there may not otherwise be a need for a particular voltage plane on that device.